Preparation method of phthalonitrile compounds

Abstract

One embodiment of the present invention provides a method for preparing phthalonitrile compounds, which comprises: step (a), adding a mixture containing phthalic acid compounds and nitrile compounds to a first reaction part for reaction; step (b), transferring the product of the above step (a) to a second reaction part connected to the above first reaction part and reacting at 350° C. to 400° C.; and step (c), obtaining phthalonitrile compounds from a discharge part connected to the above second reaction part, wherein the length of the fluid flow direction of the above second reaction part is more than 10 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

Description

Technical Field

[0001] This specification relates to a method for preparing phthalonitrile compounds using a continuous process. Background Art

[0002] Phthalonitrile compounds are important compounds used as intermediates in the preparation of fiber-forming linear polymers. In addition, phthalonitrile compounds are used as organic synthesis intermediates for various fine chemical products such as amines, amides and complex nitrogen dyes. They are also used as high-value-added raw materials for plasticizers, alkyd resin modifiers, pesticides, etc.

[0003] In the past, phthalonitrile compounds were prepared by contacting xylene compounds with ammonia and oxygen-containing gas and performing dehydration reaction in the presence of an oxidation catalyst. However, since the method uses ammonia as a harmful chemical substance, it is an ammoxidation (ammoxidation) reaction carried out under high temperature and high pressure in the presence of a catalyst, so the process is complicated, and high boiling impurities must be refined and separated by distillation, so there is a problem of being difficult to remove by-products. In addition, in the preparation method of phthalonitrile compounds in the past, the yield of the product changes according to the type of the catalyst used in the ammoxidation reaction and the ratio of the oxygen-containing gas, and the conversion rate of the xylene compounds as a precursor substance changes according to the reaction temperature, so it is difficult to control the process.

[0004] Therefore, there is an increasing demand for processes for preparing high-purity phthalonitrile compounds in an economical and environmentally friendly manner. Summary of the invention

[0005] The matters described in this specification are intended to solve the problems of the prior art. One object of this specification is to provide a method for directly preparing high-purity phthalonitrile compounds from phthalic acid compounds.

[0006] According to one aspect, a method for preparing phthalonitrile compounds is provided, the method comprising: step (a), adding a mixture containing phthalic acid compounds and nitrile compounds to a first reaction section for reaction; step (b), transferring the product of the step (a) to a second reaction section connected to the first reaction section and reacting at 350° C. to 400° C.; and step (c), obtaining the phthalonitrile compounds from a discharge section connected to the second reaction section, wherein the length of the second reaction section in the direction of fluid flow is more than 10 times the square root of the average cross-sectional area perpendicular to the direction of fluid flow.

[0007] In one embodiment, based on 100 parts by volume of the first reaction part, the capacity of the second reaction part may be 1 part by volume to 50 parts by volume.

[0008] In one embodiment, the phthalic acid compound may be isophthalic acid, terephthalic acid or a mixture thereof.

[0009] In one embodiment, the nitrile compound may be at least one selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, pivalonitrile, succinonitrile, fumaronitrile, crotononitrile and benzonitrile.

[0010] In one embodiment, the mixture in step (a) above may consist of phthalic acid compounds and nitrile compounds.

[0011] In one embodiment, in the step (a), based on 1 part by weight of the phthalic acid compound, the content of the nitrile compound is 1 part by weight to 500 parts by weight.

[0012] In one embodiment, in the step (a), the moisture content of the mixture may be less than 6,000 ppm.

[0013] In one embodiment, the reaction of step (a) may be carried out at 260° C. to 350° C. and 40 bar to 200 bar.

[0014] In one embodiment, in the step (b), the flow rate of the product of the step (a) transferred to the second reaction section may be adjusted to 100 ml / min to 5,000 ml / min.

[0015] In one embodiment, in the step (b), the contact time between the product of the step (a) and the second reaction part may be less than 60 minutes.

[0016] In one embodiment, the reaction of step (b) above may be carried out under the condition of 40 bar to 200 bar.

[0017] In one embodiment, the reaction of step (b) is carried out for 1 minute to 500 minutes.

[0018] In one embodiment, the step (c) may be a step of separating and purifying the phthalonitrile compound from the product obtained from the discharge part.

[0019] In one embodiment, the residual compound separated in the above step (c) is reused in the above step (a).

[0020] According to one aspect of the present specification, a high-purity phthalonitrile compound can be directly prepared from a phthalic acid compound in an environmentally friendly manner.

[0021] Furthermore, according to another aspect of the present specification, the amount of by-products generated is reduced and the reaction time is shortened, so that the process of preparing phthalonitrile compounds from phthalic acid compounds can be carried out more efficiently.

[0022] The effects of one aspect of the present specification are not limited to the above-mentioned effects, and should be understood to include all effects inferred from the structure of the invention described in the detailed description of the present specification or the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figures 1 to 4 A system for preparing phthalonitrile compounds used in one embodiment of the present specification is schematically shown.

[0024] Description of Reference Numerals

[0025] 100: First reaction department

[0026] 200: Second reaction unit

[0027] 300: Emissions Department

[0028] 120, 220, 320: Temperature adjustment unit

[0029] 400: Pressure regulation unit DETAILED DESCRIPTION

[0030] Hereinafter, one aspect of the present specification will be described with reference to the accompanying drawings. However, the contents of the present specification can be implemented in a variety of different forms and are not limited to the embodiments described in the present specification. In order to clearly explain one aspect of the present specification in the accompanying drawings, parts not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0031] Throughout the specification, when it is described that a component is “connected” to another component, it includes not only the case of “direct connection” but also the case of “connected with other components interposed therebetween.” Furthermore, when a component is referred to as “including (or comprising)” an element, unless expressly specified otherwise, instead of excluding any other elements, it may mean that a component may further include other elements.

[0032] In this specification, when describing a series of numerical ranges, unless otherwise specifically stated, these values ​​have a precision of significant figures provided according to standard rules in chemistry for significant figures. For example, 10 includes a range of 5.0 to 14.9, and the number 10.0 includes a range of 9.50 to 10.49.

[0033] Hereinafter, an embodiment according to the present specification will be described in detail with reference to the accompanying drawings.

[0034] Preparation method of phthalonitrile compounds

[0035] According to one aspect of the present specification, a method for preparing phthalonitrile compounds includes: step (a), adding a mixture containing phthalic acid compounds and nitrile compounds to a first reaction unit 100 for reaction; step (b), transferring the product of the above step (a) to a second reaction unit 200 connected to the above first reaction unit 100 and reacting at 350°C to 400°C; and step (c), obtaining phthalonitrile compounds from a discharge unit 300 connected to the above second reaction unit 200, wherein the length of the second reaction unit 200 in the fluid flow direction can be more than 10 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

[0036] The preparation method of the above-mentioned phthalonitrile compound can be carried out by a continuous process, for example, Figures 1 to 4 The preparation system of phthalonitrile compounds is briefly shown in the figure, but is not limited thereto.

[0037] The preparation system of the phthalonitrile compounds comprises: a first reaction unit 100; a second reaction unit 200 connected to the first reaction unit 100; and a discharge unit 300 connected to the second reaction unit 200. In the second reaction unit 200, the fluid can flow from the direction of the first reaction unit 100 to the direction of the discharge unit 300.

[0038] The first reaction unit 100 may be a tank reactor and may include a stirring device (not shown). In the first reaction unit 100, the reaction of the phthalic acid compound and the nitrile compound may be initiated and performed for the first time.

[0039] The second reaction unit 200 may be a tubular reactor having a larger length in the direction of fluid flow than in the direction perpendicular to the direction of fluid flow, and may include a stirring device (not shown). For example, the second reaction unit 200 may be a coil reactor, but is not limited thereto. Figures 1 to 4 In the figure, the fluid flow direction indicated by the thin solid arrow of the second reaction part 200 is illustrated as a straight line, but is not limited thereto. In addition to a straight line, the fluid flow direction of the second reaction part 200 may also be in a curved shape such as a coil. In the second reaction part 200, the product of the step (a) may be additionally reacted, and some by-products present in the product of the step (a) may be decomposed.

[0040] In the present specification, the length of the second reaction part 200 refers to a distance from one end connected to the first reaction part 100 to the other end connected to the discharge part 300 .

[0041] In this specification, the cross-sectional area of ​​the second reaction part 200 refers to an area perpendicular to the flow direction of the fluid.

[0042] In this specification, if the cross-sectional area of ​​the second reaction portion 200 does not change with position, the “square root of the average cross-sectional area” may refer to the square root value of the cross-sectional area; if the cross-sectional area of ​​the second reaction portion 200 changes with position, the “square root of the average cross-sectional area” may refer to S calculated according to the following mathematical formula: sqrt value.

[0043] [Mathematical formula]

[0044]

[0045] In the above formula, L is the length of the second reaction part 200, A(x) is the cross-sectional area value of the point x from the one end 0 connected to the first reaction part 100 to the other end L connected to the discharge part 300, S sqrt Means the square root of the above average cross-sectional area.

[0046] The length of the second reaction part 200 may be at least 10 times the square root of the average cross-sectional area. For example,It can be 10 times, 15 times, 20 times, 25 times, 30 times, 35 times, 40 times, 45 times, 50 times, 55 times, 60 times, 65 times, 70 times, 75 times, 80 times, 85 times, 90 times, 95 times, 100 times, 105 times, 110 times, 115 times, 120 times, 125 times, 130 times, 135 times, 140 times, 145 times, 150 times, 155 times, 160 times, 165 times, 170 times, 175 times, 180 times, 185 times, 190 times, 195 times, 200 times, 205 times, 210 times, 215 times, 220 times, 225 times, 230 times, 235 times, 240 times, 245 times, 250 times, 255 times, 260 times, 265 times, 27 0 times, 275 times, 280 times, 285 times, 290 times, 295 times, 300 times, 305 times, 310 times, 315 times, 320 times, 325 times, 330 times, 335 times, 340 times, 345 times, 350 times, 355 times, 360 times, 365 times, 370 times, 375 times, 380 times, 385 times, 390 times, 3 95 times, 400 times, 405 times, 410 times, 415 times, 420 times, 425 times, 430 times, 435 times, 440 times, 445 times, 450 times, 455 times, 460 times, 465 times, 470 times, 475 times, 480 times, 485 times, 490 times, 495 times, 500 times, 505 times, 510 times, 515 times, 520 times, 525 times, 530 times, 535 times, 540 times, 545 times, 550 times, 555 times, 560 times, 565 times, 570 times, 575 times, 580 times, 585 times, 590 times, 595 times, 600 times, 605 times, 610 times, 615 times, 620 times, 625 times, 630 times, 635 times, 640 times times, 645 times, 650 times, 655 times, 660 times, 665 times, 670 times, 675 times, 680 times, 685 times, 690 times, 695 times, 700 times, 715 times, 720 times, 725 times, 730 times, 735 times, 740 times, 745 times, 750 times, 755 times, 760 times, 765 times, 770 times, 775 times 5 times, 780 times, 785 times, 790 times, 795 times, 800 times, 805 times, 810 times, 815 times, 820 times, 825 times, 830 times, 835 times, 840 times, 845 times, 850 times, 855 times, 860 times, 865 times, 870 times, 875 times, 880 times, 885 times, 890 times, 895 times, 900 times, 905 times, 910 times, 915 times, 920 times, 925 times, 930 times, 935 times, 940 times, 945 times, 950 times, 955 times, 960 times, 965 times, 970 times, 975 times, 980 times, 985 times, 990 times, 995 times, 1,000 times, between two values ​​thereof, or more than 1,000 times, for example,It can be 10 to 1,000 times, but is not limited thereto. If the length of the second reaction unit 200 exceeds the above range, the product purity may be reduced due to insufficient control of the change of the reaction temperature and / or the reaction pressure, or the productivity may be reduced due to the excessively long process time.

[0047] Based on the capacity of the above-mentioned first reaction part 100 of 100 parts by volume, the capacity of the above-mentioned second reaction part 200 can be 1 part by volume to 50 parts by volume, for example, can be 1 part by volume, 5 parts by volume, 10 parts by volume, 15 parts by volume, 20 parts by volume, 25 parts by volume, 30 parts by volume, 35 parts by volume, 40 parts by volume, 45 parts by volume, 50 parts by volume or between two values ​​thereof, but not limited thereto. If the capacity of the above-mentioned second reaction part 200 is too large compared with the above-mentioned first reaction part 100, the process efficiency may be reduced, and if the capacity of the above-mentioned second reaction part 200 is too small, the effect of improving the purity of the product by controlling the reaction conditions may not be enough.

[0048] Figure 1 The preparation system of the phthalonitrile compound is briefly shown, and the reaction is carried out by connecting the second reaction unit 200 as a tubular reactor to the first reaction unit 100 as a tank reactor, and the product is obtained from the discharge unit 300, thereby improving the problem of reduced product purity due to changes in reaction temperature and / or reaction pressure. The first reaction unit 100 and the second reaction unit 200 are adjusted using a valve (not shown in the figure) such as a flow meter to adjust the input amount (flow rate) of the product of the above step (a) transferred to the above second reaction unit 200.

[0049] Referring to another example of the preparation system of the above-mentioned phthalonitrile compounds Figure 2 A pressure regulating unit 400 may be further included between the first reaction unit 100 and the second reaction unit 200 and / or between the second reaction unit 200 and the discharge unit 300. If the pressure regulating unit 400 is further included, the reaction pressure may be controlled more accurately.

[0050] Referring to another example of a system for preparing phthalonitrile compounds Figure 3 At least one of the first reaction part 100, the second reaction part 200 and the discharge part 300 may further include a temperature control part 120, 220, 320. The temperature adjustment part 120, 220 of the first reaction part 100 or the second reaction part 200 helps maintain a high reaction temperature in the form of surrounding each reaction part 100, 200, and the temperature adjustment part 320 of the discharge part 300 may be located at the front end of the discharge part 300 to cool the product, but is not limited thereto.

[0051] Referring to an example of a system for preparing phthalonitrile compounds Figure 4 , may include at least one of the temperature control parts 120, 220, 320 and at least one of the pressure control parts 400. The positions of the temperature control part 320 and the pressure control part 400 may be changed.

[0052] When the above-mentioned system for preparing phthalonitrile compounds is used, the purity of the final product is high and the total reaction time is shortened by more accurately controlling the reaction temperature and pressure, so that the productivity can be excellent.

[0053] The step (a) is a step of adding the reaction product to the first reaction unit 100 for reaction. After adding the mixture at room temperature, the reaction temperature and reaction pressure are set, and the mixture is stirred for a certain time for reaction, but the reaction is not limited thereto.

[0054] The phthalic acid compound may be a compound having an aromatic ring and two or more carboxyl groups. For example, the phthalic acid compound may be isophthalic acid, terephthalic acid or a mixture thereof, but is not limited thereto.

[0055] The nitrile compound may be at least one selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, pivalonitrile, succinonitrile, fumaronitrile, crotononitrile and benzonitrile, but is not limited thereto. The nitrile compound may be a reactant or a solvent.

[0056] In the preparation method of the above-mentioned phthalonitrile compound, the reaction can be carried out without including a single additive such as ammonia, high concentration oxygen or a catalyst. Therefore, the mixture of the above-mentioned step (a) can be composed of a phthalic acid compound and a nitrile compound, but is not limited thereto. For example, the above-mentioned mixture can be formed by dissolving a solid phthalic acid compound in a nitrile compound solvent, but is not limited thereto.

[0057] In the above step (a), based on 1 part by weight of the above phthalic acid compound, the content of the above nitrile compound can be 1 part by weight to 500 parts by weight. For example, based on 1 part by weight of the above phthalic acid compound, the content of the above nitrile compound can be 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 150 parts by weight, 160 parts by weight, 170 parts by weight, 180 parts by weight, 190 parts by weight, 200 parts by weight, 210 parts by weight, 220 parts by weight, 230 parts by weight, 240 parts by weight, 250 parts by weight, 260 parts by weight, 270 parts by weight, 280 parts by weight, 290 parts by weight, 300 parts by weight, 310 parts by weight, 320 parts by weight, 330 parts by weight, 340 parts by weight, 350 parts by weight, 360 parts by weight, 370 parts by weight, 380 parts by weight, 390 parts by weight, 400 parts by weight, 410 parts by weight, 420 parts by weight, 430 parts by weight, 440 parts by weight, 450 parts 115 parts by weight, 120 parts by weight, 125 parts by weight, 130 parts by weight, 135 parts by weight, 145 parts by weight, 150 parts by weight, 155 parts by weight, 160 parts by weight, 165 parts by weight, 170 parts by weight, 175 parts by weight, 180 parts by weight, 185 parts by weight, 190 parts by weight, 195 parts by weight, 200 parts by weight, 205 parts by weight, 220 parts by weight, 225 parts by weight, 220 parts by weight, 225 parts by weight, 230 parts by weight, 235 parts by weight, 245 parts by weight , 250 parts by weight, 255 parts by weight, 260 parts by weight, 265 parts by weight, 270 parts by weight, 275 parts by weight, 280 parts by weight, 285 parts by weight, 290 parts by weight, 295 parts by weight, 300 parts by weight, 305 parts by weight, 330 parts by weight, 335 parts by weight, 320 parts by weight, 325 parts by weight, 330 parts by weight, 335 parts by weight, 345 parts by weight, 350 parts by weight, 355 parts by weight, 360 parts by weight, 365 parts by weight, 370 parts by weight, 375 parts by weight The nitrile compounds of the present invention can be used to prepare the phthalic acid compounds of the present invention.The nitrile compounds of the present invention can be used to prepare the phthalic acid compounds of the present invention.

[0058] In the step (a), the moisture content of the mixture may be less than 6,000 ppm. For example, the moisture content of the mixture may be less than 6,000 ppm, less than 5,000 ppm, less than 4,000 ppm, less than 3,000 ppm, less than 2,000 ppm, less than 1,000 ppm, less than 750 ppm, less than 500 ppm or less than 250 ppm. The lower the moisture content of the mixture, the higher the purity of the product.

[0059] The reaction of step (a) can be carried out at 260° C. to 350° C. and 40 to 200 bar. For example, the reaction can be carried out at 260° C., 265° C., 270° C., 275° C., 280° C., 285° C., 290° C., 295° C., 300° C., 305° C., 310° C., 315° C., 320° C., 325° C., 330° C., 335° C., 340° C., 345° C., 350° C. or at a reaction temperature in a range between two values ​​thereof, and can be carried out at 40 bar, 45 bar, 50 bar, 55 bar, 60 bar, 65 bar. , 70 bar, 75 bar, 80 bar, 85 bar, 90 bar, 95 bar, 100 bar, 105 bar, 110 bar, 115 bar, 120 bar, 125 bar, 130 bar, 135 bar, 140 bar, 145 bar, 150 bar, 155 bar, 160 bar, 165 bar, 170 bar, 175 bar, 180 bar, 185 bar, 190 bar, 195 bar, 200 bar or a reaction pressure within a range between two values ​​thereof. If the reaction temperature in the above step (a) is too low, the purity of the product may be reduced or the reaction may not be carried out. If the reaction temperature is too high, the generation of by-products may increase and the purity may be reduced. If the reaction pressure in the above step (a) is too low, the reaction may not be carried out. If the reaction pressure is too high, the safety may be reduced.

[0060] The reaction of the above-mentioned steps (a) can be carried out for 1 minute to 150 minutes. For example, the above-mentioned steps (a) can be carried out for 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 145 minutes or 150 minutes, and the intermediate range can be included. If the reaction time of the above-mentioned steps (a) exceeds the above range, impurities may be formed and purity may be reduced, or reaction may be insufficient and yield may be reduced.

[0061] The above-mentioned step (b) is a step of transferring the product of the above-mentioned step (a) to the above-mentioned second reaction unit 200 for reaction. After setting the reaction temperature and reaction pressure of the above-mentioned second reaction unit 200, the product of the above-mentioned step (a) can be transferred at a constant flow rate and reacted for a predetermined time while stirring, but it is not limited to this.

[0062] In the step (b), the flow rate of the product of the step (a) transferred to the second reaction unit 200 may be adjusted to 100 ml / min to 5,000 ml / min. For example, the flow rate may be 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, 600 ml / min, 700 ml / min, 800 ml / min, 900 ml / min, 1,000 ml / min, 1,100 ml / min, 1,200 ml / min, 1,300 ml / min, 1,400 ml / min, 1,500 ml / min, 1,600 ml / min, 1,700 ml / min, 1,800 ml / min, 1,900 ml / min, 2,000 ml / min, 2,100 ml / min, 2,200 ml / min, 2,300 ml / min, 2,400 ml / min, 2,500 ml / min, 2,600 ml / min. 3,800ml / min, 3,900ml / min, 4,000ml / min, 4,100ml / min, 4,200ml / min, 4,300ml / min, 4,400ml / min, 4,500ml / min, 4,600ml / min, 4,700ml / min, 4,800ml / min, 4,900ml / min, 5,000ml / min or in a range between two of the values. If the flow rate is lower than the range, the contact time between the product of step (a) and the second reaction unit 200 is too long, thereby reducing process efficiency and increasing by-products, thereby reducing the purity of the product. If the flow rate is higher than the range, the contact time may be excessively shortened, and the purity of the product may be reduced. A mass flow controller (MFC) may be used to adjust the flow rate, but is not limited thereto.

[0063] The reaction of step (b) can be carried out at 350° C. to 400° C. For example, the reaction can be carried out at a reaction temperature of 350° C., 355° C., 360° C., 365° C., 370° C., 375° C., 380° C., 385° C., 390° C., 395° C., 400° C., or a range between two values ​​thereof. If the reaction temperature of step (b) is lower than the above range, the purity of the product may be reduced or the reaction may not be carried out. If the reaction temperature of step (b) is higher than the above range, the generation of by-products may increase, and the purity of the product may be reduced.

[0064] The reaction temperature of the step (b) may be higher than the reaction temperature of the step (a). By setting the reaction temperature of the second reactor 200 to be 350°C to 400°C higher than the reaction temperature of the first reactor 100, some by-products generated by the reaction of the step (a) may be decomposed, and the decomposed by-products may be converted into target products through the reaction, thereby preparing a high-purity phthalonitrile compound with a reduced by-product ratio. In one embodiment, the decomposed by-product may be N-acetyl-3-cyano-benzamide (3-CBAA), but is not limited thereto.

[0065] In the above-mentioned step (b), the contact time of the product of the above-mentioned step (a) with the above-mentioned second reaction part 200 can be less than 60 minutes. For example, the above-mentioned contact time can be less than 60 minutes, less than 55 minutes, less than 50 minutes, less than 45 minutes, less than 40 minutes, less than 35 minutes, less than 30 minutes, less than 25 minutes, less than 20 minutes, less than 15 minutes, less than 10 minutes, less than 5 minutes or less than 1 minute. When the contact time of the product of the above-mentioned step (a) with the above-mentioned second reaction part 200 meets the above-mentioned range, part of the by-products produced by the reaction of the above-mentioned step (a) is decomposed and converted into the target product, thereby increasing the purity of the product. If the above-mentioned contact time is longer than the above-mentioned range, the by-products may increase and the purity of the product may decrease. The above-mentioned contact time can be controlled by adjusting the volume of the above-mentioned second reaction part 200, the flow rate of the product of the above-mentioned step (a) transferred to the above-mentioned second reaction part 200, or at least one of the discharge amount of the reactant and the product per unit flow, but is not limited thereto. The contact time may refer to a residence time in the second reaction unit 200 .

[0066] The reaction of the above step (b) can be carried out under the conditions of 40 bar to 200 bar. For example, it can be carried out under the reaction pressure of 40 bar, 45 bar, 50 bar, 55 bar, 60 bar, 65 bar, 70 bar, 75 bar, 80 bar, 85 bar, 90 bar, 95 bar, 100 bar, 105 bar, 110 bar, 115 bar, 120 bar, 125 bar, 130 bar, 135 bar, 140 bar, 145 bar, 150 bar, 155 bar, 160 bar, 165 bar, 170 bar, 175 bar, 180 bar, 185 bar, 190 bar, 195 bar, 200 bar or in the range between two values ​​thereof. If the reaction pressure in the above step (b) is too low, the reaction may not be carried out, and if the reaction pressure is too high, safety may be reduced. The reaction pressure of the above step (b) can be carried out under the same conditions as the reaction pressure of the above step (a), but is not limited thereto.

[0067] The above step (b) may be performed for 1 minute to 500 minutes. For example, the above step (b) can be performed for 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 145 minutes, 150 minutes, 155 minutes, 160 minutes, 165 minutes, 170 minutes, 175 minutes, 180 minutes, 185 minutes, 190 minutes, 195 minutes, 200 minutes, 205 minutes, 220 minutes, 225 minutes, 220 minutes, 225 minutes, 230 minutes, 235 minutes, 245 minutes, 250 minutes, 255 minutes, 260 minutes, 265 minutes, 270 minutes, 275 minutes, 280 minutes, 285 minutes, 290 minutes, 295 minutes, 300 minutes, 305 minutes, 330 minutes, 335 minutes, 320 minutes, 325 minutes, 330 minutes, 335 minutes, 345 minutes, 350 minutes, 355 minutes, 360 minutes, 365 minutes, 370 minutes, 375 minutes, 380 minutes, 385 minutes, 390 minutes, 395 minutes, 400 minutes, 405 minutes, 440 minutes, 445 minutes, 420 minutes, 425 minutes, 430 minutes, 435 minutes, 445 minutes, 450 minutes, 455 minutes, 460 minutes, 465 minutes, 470 minutes, 475 minutes, 480 minutes, 485 minutes, 490 minutes, 495 minutes or 500 minutes, and ranges therebetween may also be included. As the reaction time of the above step (b) increases, the purity of the product may increase, but if the reaction time is too long, the productivity may decrease.

[0068] In the above step (b), the product that has been reacted to a certain level in the first reaction section is subjected to a split reaction at a high temperature by using the second reaction section, thereby improving the overall reaction rate, yield and purity.

[0069] The reaction of the above step (a) and step (b) may be di-nitrilation by direct substitution reaction of a carboxyl group and a nitrile group, and an example thereof can be represented by the following reaction formula.

[0070]

[0071] In the above reaction formula, R is an aromatic ring such as phenylene, and R' can be an alkyl group having 1 to 20 carbon atoms, for example, methyl, ethyl, isopropyl, tert-butyl, etc.

[0072] The above step (c) may be a step of separating and refining phthalonitrile compounds from the product obtained by the above discharge unit 300. The above separation and purification may be a process of separating into phthalonitrile compounds and residual compounds, and may be performed by various well-known methods such as distillation separation. For example, the above residual compounds may include at least one selected from the group consisting of unreacted phthalic acid compounds, unreacted nitrile compounds, and phthalic acid nitrile compounds in which a part of the carboxyl groups of phthalic acid compounds react, but is not limited thereto.

[0073] The residual compounds other than the phthalonitrile compounds separated in the above step (c) can be reused in the above step (a). The preparation method of the phthalonitrile compounds according to one embodiment of the present specification can be performed without using a separate additive such as a catalyst, so the residual compounds can be reused without additional refining.

[0074] In the above-mentioned preparation method of phthalonitrile compounds, the purity of the phthalonitrile compounds as products can be 60% or more, 65% or more, 70% or more, 80% or more, 85% or more, 90% or more or 95% or more.

[0075] Hereinafter, the embodiments of this specification will be described in more detail. However, the following experimental results are only representative experimental results in the above-mentioned embodiments, and the embodiments etc. should not be construed as limiting or restricting the scope and content of this specification. The effects of various embodiments of this specification that are not clearly presented below are specifically recorded in the corresponding parts.

[0076] ( Reactor )

[0077] First reactor: a tank reactor with a capacity of 100 parts by volume and equipped with a stirrer

[0078] Second reactor: a tubular reactor with a length of 670 times the square root of the cross-sectional area and a capacity of 6 parts by volume

[0079] Example 1

[0080] 75 g of isophthalic acid (IPA) and 1,500 g of acetonitrile (ACN) were added to a first reactor equipped with a stirrer. Nitrogen was replaced three times at a pressure of 2 to 3 bar inside the first reactor. The first reactor was stirred at 600 rpm and the internal temperature was raised to 280°C. After reacting for 1 hour while maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar, the reactant was transferred to a second reactor at a flow rate of 1,000 ml / min at a reaction temperature of 350 to 400°C and a reaction pressure of 85 to 90 bar. The product obtained at the end of the second reactor was transferred to a distillation tower and then vacuum distilled to remove acetonitrile and acetic acid. The removed acetonitrile was reused. The residual product was analyzed by gas chromatography (GPC) to confirm the purity, and the isophthalonitrile (IPN) of the separated by-product was obtained by additional purification.

[0081] Example 2

[0082] 75 g to 214.3 g of isophthalic acid and 1,500 g of acetonitrile are added to a first reactor equipped with a stirrer. Nitrogen is replaced three times at a pressure of 2 to 3 bar inside the first reactor. The first reactor is stirred at 600 rpm and the internal temperature is raised to 280°C. After reacting for 1 hour while maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar, the reactant is transferred to a second reactor at a flow rate of 1,000 ml / min at a reaction temperature of 400°C and a reaction pressure of 85 to 90 bar. The product obtained at the end of the second reactor is transferred to a distillation tower and then vacuum distilled to remove acetonitrile and acetic acid. The removed acetonitrile is reused. For the residual product, the purity is confirmed by gas chromatography analysis every 30 minutes, and isophthalonitrile is obtained by additional refining to separate by-products.

[0083] Comparative Example 1

[0084] 150g of isophthalic acid and 1,500g of acetonitrile are added to a first reactor equipped with an agitator to form a reaction system. Inside the first reactor, nitrogen is replaced 3 times at a pressure of 2 to 3 bars. The first reactor is stirred at 600rpm and the internal temperature is raised to 280°C. While maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bars, the reaction is carried out for 4 hours. After the reaction is completed, the reaction system is cooled to room temperature. Then, the reaction system is distilled under vacuum to remove acetonitrile and acetic acid. The removed acetonitrile is reused. For the residual product, the purity is confirmed by gas chromatography analysis, and isophthalonitrile is obtained by additional refining and separation of by-products.

[0085] Comparative Example 2

[0086] 75 g of isophthalic acid and 1,500 g of acetonitrile are added to a first reactor equipped with a stirrer. Inside the first reactor, nitrogen is replaced three times at a pressure of 2 to 3 bar. The first reactor is stirred at 600 rpm and the internal temperature is raised to 280°C. After reacting for 1 hour while maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar, the reactant is transferred to a second reactor at a flow rate of 1,000 ml / min at a reaction temperature of 280 to 300°C and a reaction pressure of 85 to 90 bar. The product obtained at the end of the second reactor is transferred to a distillation tower and then vacuum distilled to remove acetonitrile and acetic acid. The removed acetonitrile is reused. For the residual product, the purity is confirmed by gas chromatography analysis, and isophthalonitrile is obtained by additional refining to separate by-products.

[0087] Comparative Example 3

[0088] 150 g of isophthalic acid and 1,500 g of acetonitrile are added to a first reactor equipped with a stirrer. Inside the first reactor, nitrogen is replaced three times at a pressure of 2 to 3 bar. The first reactor is stirred at 600 rpm and the internal temperature is raised to 280°C. After reacting for 1 hour while maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar, the reactant is transferred to a second reactor at a flow rate of 500 to 1,000 ml / min at a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar. The product obtained at the end of the second reactor is transferred to a distillation tower and then vacuum distilled to remove acetonitrile and acetic acid. The removed acetonitrile is reused. For the residual product, the purity is confirmed by gas chromatography analysis, and isophthalonitrile is obtained by additional refining to separate by-products.

[0089] Comparative Example 4

[0090] 75 g to 214.3 g of isophthalic acid and 1,500 g of acetonitrile are added to a first reactor equipped with a stirrer. Inside the first reactor, nitrogen is replaced three times at a pressure of 2 to 3 bar. The first reactor is stirred at 600 rpm and the internal temperature is raised to 280°C. After reacting for 1 hour while maintaining a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar, the reactant is transferred to a second reactor at a flow rate of 1,000 ml / min at a reaction temperature of 280°C and a reaction pressure of 85 to 90 bar. The product obtained at the end of the second reactor is transferred to a distillation tower and then vacuum distilled to remove acetonitrile and acetic acid. The removed acetonitrile is reused. For the residual product, the purity is confirmed by gas chromatography analysis, and isophthalonitrile is obtained by additional refining to separate by-products.

[0091] The reaction conditions and gas chromatography analysis results of the above-mentioned Examples and Comparative Examples are summarized in the following Table 1. As a result of gas chromatography analysis, 3-cyanobenzoic acid (3-CBAc), 3-cyanobenzamide (3-CBAm) and N-acetyl-3-cyano-benzamide (3-CBAA) were detected as by-products.

[0092] Table 1

[0093]

[0094] With reference to Example 1 and Comparative Example 2, the higher the reaction temperature of the second reactor, the higher the purity of the isophthalonitrile as the product.

[0095] Referring to Example 2-1 to Example 2-5, as the reaction time increases, the purity of isophthalonitrile as the product increases.

[0096] In addition, referring to Examples 2-5 to 2-8 and Comparative Example 4, the higher the amount of acetonitrile added relative to isophthalic acid, the higher the purity of isophthalic acid. Therefore, it is confirmed that when the reaction temperature of the second reactor is 400°C and the amount of acetonitrile added is 20 parts by weight based on 1 part by weight of isophthalic acid, the purity of Example 2-5 is the highest.

[0097] It was confirmed that the proportion of 3-CBAA in the examples where the reaction temperature of the second reactor was 350°C to 400°C was less than 1.0%, and the proportion of 3-CBAA as a by-product was lower than that in the comparative examples where the reaction temperature of the second reactor was 280°C to 300°C.

[0098] Referring to Comparative Example 3, as the flow rate of the reactant transferred from the first reactor to the second reactor increases, the purity of isophthalonitrile increases.

[0099] Under the conditions of the same reactants and reaction temperature, when comparing Comparative Example 1 which is a batch process using only the first reactor and Comparative Example 3 which is a continuous process using the first reactor and the second reactor, the purity of isophthalonitrile is higher in the continuous process even though the reaction time is shorter than in the batch process.

[0100] Different from the preparation process of the existing ammoxidation reaction using harmful compounds such as ammonia and acid catalysts, in one embodiment of the present specification, phthalic acid compounds can be used to prepare phthalonitrile compounds with high yield without adding a separate catalyst or additive. In addition, by using a continuous process, a product of higher purity can be prepared with a shorter reaction time than the comparative example 1 of performing intermittent reaction, and by setting the reaction temperature of the second reactor of the continuous process to a high temperature, the ratio of 3-CBAA as a by-product is reduced, so that high-purity isophthalonitrile can be prepared. This is because the 3-CBAA produced in the first reactor is decomposed and converted into isophthalonitrile when passing through the second reactor at high temperature.

[0101] Specifically, in the above-described embodiment, use isophthalic acid as phthalic acid compounds as reactant, use acetonitrile as organic nitrile as solvent and reactant.By directly heating the mixture under the state of not adding independent catalyst or adduct, form high temperature and high pressure reaction conditions, and cause acid-nitrile exchange reaction, directly generate phthalonitrile compounds.In addition, above-mentioned reaction is divided into tank reactor and tubular reactor to carry out, by the temperature setting of tubular reactor is high, thereby prepare high purity product in the shorter time.As a result, the refining and separation of final product are easier.

[0102] The above description of this specification is only illustrative, and anyone skilled in the art of the present specification will understand that it can be easily transformed into other specific forms without changing the technical ideas or essential features of the present specification. Therefore, it should be understood that the above-mentioned embodiments are only illustrative in all aspects, but are not limited to this. For example, each structural component described as a single type can also be implemented in a dispersed manner, and similarly, the structural components described in a dispersed manner can also be implemented in a combined form.

[0103] The scope of the present specification is indicated by the appended claims rather than the above detailed description, and all changes or modifications derived from the meaning, scope and equivalent concepts of the claims should be interpreted as being included in the scope of the present specification.

Claims

1. A method for preparing a phthalonitrile compound, characterized in that: include: Step (a), adding a mixture containing a phthalic acid compound and a nitrile compound to a first reaction part for reaction; Step (b), transferring the product of step (a) to a second reaction section connected to the first reaction section as a tubular reactor and reacting at 350° C. to 400° C. and 40 bar to 200 bar; and Step (c), obtaining a phthalonitrile compound from a discharge part connected to the second reaction part, The reaction in step (a) is carried out at 260°C to 350°C and 40 bar to 200 bar. In the step (b), the flow rate of the product of the step (a) transferred to the second reaction section is adjusted to 100 ml / min to 5,000 ml / min. The length of the second reaction portion in the fluid flow direction is at least 10 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

2. The method for preparing phthalonitrile compounds according to claim 1, wherein The capacity of the second reaction part is 1 part by volume to 50 parts by volume based on 100 parts by volume of the capacity of the first reaction part.

3. The method for preparing phthalonitrile compounds according to claim 1, wherein The above-mentioned phthalic acid compound is isophthalic acid, terephthalic acid or a mixture thereof.

4. The method for preparing phthalonitrile compounds according to claim 1, wherein The nitrile compound is at least one selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, pivalonitrile, succinonitrile, fumaronitrile, crotononitrile and benzonitrile.

5. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: The mixture in the above step (a) consists of phthalic acid compounds and nitrile compounds.

6. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: In the step (a), based on 1 part by weight of the phthalic acid compound, the content of the nitrile compound is 1 part by weight to 500 parts by weight.

7. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: In the step (a), the moisture content of the mixture is less than 6,000 ppm.

8. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: In the step (b), the contact time between the product of the step (a) and the second reaction part is 60 minutes or less.

9. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: The reaction of the above step (b) is carried out for 1 minute to 500 minutes.

10. The method for preparing phthalonitrile compounds according to claim 1, characterized in that: The step (c) is a step of separating and purifying the phthalonitrile compound from the product obtained from the discharge section.

11. The method for preparing phthalonitrile compounds according to claim 10, characterized in that: The residual compound separated in the above step (c) is reused in the above step (a).

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